Tuning the carrier scattering mechanism to effectively improve the thermoelectric properties

Abstract

A high thermoelectric power factor not only enables a potentially high figure of merit ZT but also leads to a large output power density, and hence it is pivotal to find an effective route to improve the power factor.

Achieving band convergence by tuning the bonding ionicity in n‐type Mg3Sb2

“…The anisotropies of these parameters are not considered, since we would like to compare our results to polycrystalline samples in experiments. The calculated power factor of stoichiometric Mg 3 Sb 2 is around 5.5 μWcm −1 K −2 , consistent with the experimental power factor at 300 K . For doped Mg 3 Sb 2 , we assume the E n and C are unchanged, and thus the power factor variations in Figure b only reflect the variations of band structures.…”

“…also obtained the zT value of 1.65 in the same system, and attributed the advanced TE properties to the complex electronic conduction band minimum (CBM) . Other works on n‐type Mg 3 Sb 2 ‐related compounds focused on the reduction of the ionic impurity scattering . The net result of these optimizations is that n‐type Mg 3 Sb 2 is one of the most promising new TEs from the point of view of energy conversion efficiency.…”

“…p‐type Mg 3 Sb 2 ‐based compounds, such as Zn‐doped, Na‐doped, Ag‐doped, and co‐doping of Na and Zn, have limited TE performance due to electrical transport properties inferior to the best materials, mostly because of the low band degenerate valence band maximum (VBM) at Γ point . In contrast, recently discovered n‐type Mg 3 Sb 2 ‐based compounds show very promising TE properties . Tamaki et al .…”

Rapid One‐Step Synthesis and Compaction of High‐Performance n‐Type Mg3Sb2 Thermoelectrics

“…Recently n‐type Mg 3 Sb 2 ‐based compounds have been intensively studied because of their outstanding TE performance as well as the low‐cost and abundantly available constituent elements . Exceptional n‐type TE properties were first reported in Te‐doped Mg 3+ δ Sb 1.5 Bi 0.5 with a high zT value of about 1.6 at 725 K by Tamaki et al .…”

Enhanced Thermoelectric Performance in N‐Type Mg3.2Sb1.5Bi0.5 by La or Ce Doping into Mg

“…This has inspired the further enhancement of electron concentration by extrinsic doping, typically by a chalcogen 9–12,15–17. Combined with the alloying of Mg 3 Bi 2 to decrease the lattice thermal conductivity, ZT values higher than 1.5 have been widely achieved 9,11,13,14,16,18–21. Furthermore, an enhanced room‐temperature ZT , which is close to that of the commercially available Bi 2 Te 3 , has been obtained in chalcogen‐doped Mg 3 Sb 2 ‐based materials by co‐doping with transition metals (e.g., Mn),17,18 tuning the mole ratio of Bi and Sb,17,22 and deliberately increasing the grain size,15,18,19,23 all of which result in increased carrier mobility.…”